The lifetime of the b3{logical and with double overbar}+ state of CO was measured at six different pressures; 10, 25, 50, 75, 100, and 125 μ; by observing the decay of the (0, 1), (0, 2), (0, 3), and (0, 4) bands of the 3+ system. No pressure dependence of the lifetime was noted. No variation in lifetime was observed over the above progression of states so that transition moment can be assumed constant for transitions arising from the v' = 0 level. The measured lifetimes from the (0, 1), (0, 2), (0, 3), and (0, 4) transitions are 57.5±0.9, 57.2±1.0, 58.8±0.7, and 56.9±1.5 nsec, respectively. The average lifetime of the v' = 0 state was 57.6±1.2 nsec. © 1970.